Deprotection of t-Butyldimethylsiloxy (TBDMS) Protecting Group with Catalytic Copper (II) Chloride Dihydrate

The protection of functional group is unavoidable in multi-step organic synthesis. Alongwith tetrahydropyranyl (THP) ethers, t-butyldimethylsilyl (TBDMS) ethers have beenwidely used for protecting hydroxyl groups. TBDMS ether is more stable to hydrolysisthan trimethylsilyl ether, but is still readily cleaved by a variety of selective conditionsl.The deprotection of TBDMS is usually under mild acidic conditions [AcOH/H,O/THF,3t l: l', or BF, Et,O/CHCI,', etc. '], or with a fluoride…     

Copper(II) catalyzed heterobenzylic C(sp3)-H activation: Two efficient halogenation methodologies towards heterobenzyl halides

Two practical and simple synthetic methodologies towards various heterobenzyl halides were developed. A series of 2-halomethylquinolines were readily prepared by the one-pot reaction of 2-methylquinolines with CuX (X?=?I, Br, Cl) and TBHP in CH₃CN. A large variety of heterobenzyl iodides, including 2-iodomethylquinolines, 2-iodomethylquinoxalines, 2-iodiomethylbenzooxazole, and 2-iodiomethylbenzothiazole, were efficiently synthesized by one-pot reaction of 2-methylheterocycles with iodine in the presence of CuSO₄·5H₂O in CH₃CN.     

The influence of the cyclopeptide sequence on its coordination abilities towards Cu(II)

The binding abilities of three novel cyclohexapeptides with three histidyl residues are presented. The analysis of the potentiometric and spectroscopic results, together with the theoretical calculations, allow the characterization of the coordination abilities of c(GlyHisArgHisHisGly), c(GlyHisArgHisGlyHis), c(GlyHisArgGlyHisHis) towards copper(II) ions and the impact of the peptide sequence on the efficiency in Cu(II) binding, and the type of formed complexes is also presented.     

Copper(II) catalyzed selective oxidation of primary alcohols to aldehydes with atmospheric oxygen

Copper(II) complex 1 selectively catalyzes the oxidation of primary alcohols to aldehydes in high yields by atmospheric oxygen in the presence of TEMPO. This procedure does not require an additive and the catalyst 1 is recyclable without loss of activity.     

Copper(II) ion-selective microelectrochemical transistor

A device has been developed for the measurement of copper(II) ions (Cu²⁺) in aqueous medium. The device reported here is an electrochemical transistor which consists of two platinum electrodes separated by 100 μm spacing and bridged with an anodically grown film of polycarbazole. Polycarbazole film (undoped form) is observed to be highly selective for the Cu(II) ions. In a completed device, the conductivity of the polycarbazole film changes on addition of Cu(II) ions. The change in conductivity is attributed to the conformational changes in the polymer phase on occupation of the Cu(II) ions, without affecting electron/proton transfer. The device turns on by adding 2.5 × 10⁻⁶ M Cu(II) ions and reaches a saturation region beyond 10⁻⁴ M Cu(II) ion concentrations. In the above concentration range, the device response [I _D vs. log Cu(II) ion concentration] is linear. The selectivity of the device for other metal ions such as Cu(I), Ni(II), Co(II), Fe(II), Fe(III), Zn(II) and Pb(II) is also studied. Received: 6 April 1999 / Accepted: 20 August 1999     

Copper(II), palladium(II) and platinum(II) chloride complexes with 5-amino-2-tert-butyltetrazole: Synthesis, characterization and cytotoxicity

Complexes CuL₃Cl₂, PdL₂Cl₂ and PtL₂Cl₂, where L is a novel ligand from the series of 2-substituted 5-aminotetrazoles, namely 5-amino-2-tert-butyltetrazole (1), have been synthesized by the reaction of metal(II) chlorides with 1 and characterized by IR spectroscopy, thermal and X-ray analyses. The crystallographic structural analysis of these complexes revealed that 1 acts as a monodentate ligand coordinated to the metal via endocyclic N4 atom. Platinum complex demonstrates promising cytotoxicity against human cervical carcinoma cells with IC₅₀ value average between those of cisplatin and carboplatin.     

Thermodynamics of Copper(II) Complexes of Diamino Diamides in Aqueous Solution

The equilibria occurring in aqueous solutions of N,N′-bis(β-carbamoylethyl)ethylenediamine, N,N′-bis(β-carbamoylethyl)trimethylenediamine, N,N′-bis(β-carbamoylethyl)-1,2-propylenediamine, and N,N′-bis(β-carbamoylethyl)-2-hydroxytrimethylenediamine with protons and copper(II) ions as well as the deprotonation reactions of the copper (II) complexes of these four ligands have been studied by calorimetry at T=25.0°C and I=0.10 mol dm^?3 (NaClO₄). The enthalpy changes and the entropy changes for these reactions are reported and discussed.     

Studies on mononuclear chelates derived from substituted Schiff-base ligands (part 6): synthesis and characterization of a new 3-ethoxysalicyliden- p -aminoacetophenoneoxime and its complexes with cobalt(II), nickel(II), copper(II) and zinc(II)

Schiff-base complexes of cobalt(II), nickel(II), copper(II) and, zinc(II) with 3-ethoxysalicyliden-p-aminoacetophenoneoxime (HL) were prepared and characterized on the basis of elemental analyses, IR, ¹H- and ¹³C-NMR, electronic spectra, magnetic susceptibility measurements, molar conductivity and thermogravimetric analyses (TGA). A tetrahedral geometry has been assigned to the complexes.     

Copper(II) complexes with bioactive carboxyamide: synthesis, characterization and biological activity

Complexes of Cu(II) with bioactive carboxyamide ligands N',N'-bis(3-carboxy-1-oxoprop-2-enyl)2-amino-N-arylbenzamidine, N',N'-bis(3-carboxy-1-oxopropanyl)2-amino-N-arylbenzamidine and N',N'-bis(3-carboxy-1-oxophenelenyl)2-amino-N-arylbenzamidine have been synthesized and characterized by various physico-chemical techniques. Mass spectrum explains the successive degradation of the molecular species in solution and justifies ML complexes. Vibrational spectra indicate coordination of amide and carboxylate oxygen of the ligands along with water molecules. Electronic spectra and magnetic susceptibility measurements reveal octahedral geometry for Cu(II) complexes. The EPR of the reported complex show g( parallel)>g( perpendicular)>2.0023 and G value within the range 2.08-4.49 are consistent with [Formula: see text] ground state in an octahedral geometry. The voltammogram of the copper(II) complex shows a quasi-reversible redox process and a simple one electron process assignable to the Cu(II)/Cu(I) couple. Kinetic and thermodynamic parameters were computed from the thermal data using Coats and Redfern method, which confirm first order kinetics. The bio-efficacy of the ligands and its copper complexes have been examined against the growth of bacteria and pathogenic fungi in vitro to evaluate their antimicrobial potential. The results indicate that the ligand and its metal complexes possess notable antimicrobial properties.     

EPR Spectra of Copper(II) Complexes with N,N-Dialkyl Amino Acids. The Influence of Water dissolved in Organic Solvents on the Copper(II) Coordination Sphere

EPR spectra of four bis(N,N-dialkyl-L-α-aminoacidato) copper(II) complexes were studied with the aim to determine the effect of the water molecules dissolved in organic solvents on the electronic states of copper(II). It was shown that water dissolved in methylene chloride or dioxan influence the copper(II) electronic states. If the amino acid side chains are long enough to form the aliphatic intramolecular van der Waals contacts, the water molecules will induce the change in the conformation of the whole complex.     

Darstellung und Kristallstruktur von Kupfer(II)-monofluorophosphat-Dihydrat CuPO3F · 2H2O

Salts of Halogenophosphoric Acids. XVII. Preparation and Crystal Structure of Copper(II) Monofluorophosphate Dihydrate CuPO₃F · 2H₂O Copper(II) monofluorophosphate dihydrate, CuPO₃F · 2H₂O 1 was obtained by the reaction of aqueous NH₄HPO₃F and acid (NH₄)₂PO₃F solutions, respectively, using acetone or ethanol as precipitating agents. The thermal dehydration of 1 gives the water-free copper monofluorophosphate CuPO₃F ( 2 ). 1 crystallizes in the monoclinic space group P2₁/c with a = 761,44, b = 780,97, c = 921,02 pm, β = 112,94° and Z = 4.     

Trisannelated Benzene Synthesis by Copper(II) Chloride

Different ketones such as cyclohexanone, cyclopentanone, acetophenone, 2‐acetonaphthalene, 4‐methylcyclohexanone in the presence of an hydrous CuCl₂ (catalytic amounts) at reflux condition for 2–4 hours, without using a solvent led to dimers 2‐(1‐cyclohexane‐1‐yl)‐cyclohexanone 6 , 2‐cyclopentylidene cyclopentanone 10 , trimer dodecahydrotriphenylene (DTP) 4 , trindan (tricyclopentabenzene) 9 , 1,3,5‐ triphenylbenzene (TBP) 12a , 1,3,5‐tri β‐naphthylbenzene 12b and dodecahydro‐2,6,10‐trimethyltriphenylenes 17 and 18 .     

Analytical Use of Copper (II)-Neocuproine in The Spectrophotometric Determination of Hydrazines

Abstract

This work characterizes a newly developed, sensitive and convenient spectrophotometric procedure for determination of sub-ppm concentrations of hydrazine and its organic derivatives. The method is based on formation of the cuprous neocuproine chelate after reaction of hydrazines with a prepared aqueous solution of the copper (II)-neocuproine complex. The cuprous chelate is then directly measured in aqueous solution at 458 nm. The effect of several experimental conditions influencing the reaction are presented and the method was employed for the analyis of 5 different hydrazine compounds. The standard deviation did not exceed ± 0.47%.     

Structures of Nickel(II) and Copper(II) Complexes of 14-Membered Macrocyclic Quadridentate Ligands

The structures of 41 Ni(II) and 17 Cu(II) complexes of macrocyclic quadridentate ligands have been analyzed, and are discussed about bond lengths, bond angles, conformations, and configurations, upon which many conclusions are formed. The inter- or intra-molecular hydrogen bonds exist among ligands and hydrates in many compounds and play an important role in the structures. There are exhibited two distinct peaks on the histogram of the average Ni-N distances, corresponding to four coordination and six coordination; these average Ni-N distances are 1.95(4) Å and 2.10(5) Å, respectively. The most probable structures of Ni(II) macrocyclic compounds have coordination number six for the metal ion, chair forms for six-membered rings, planar structure for the metal ion and the four donor atoms of the quadridentate ligand and an inversion center at the central metal ion.     

A Simple Spectrophotometric Method for the Determination of Adrenaline by Reaction with Copper(II)-Neocuproine

Abstract

A new facile and sensitive spectrophotometric procedure for the quantitative determination of adrenaline has been established. The method is based principally on the interaction of the compound with Cu(II)-neocuproine and subsequent measurement of the cuprous neocuproine chelate produced in the reaction at 458 nm. Optimization of the reaction conditions was conducted. Beer's law was obeyed in the concentration range 0.4-2.4 ppm of adrenaline. The method finally developed has been successfully applied for the assay of the drug in some of its pharmaceutical formulations.     

Copper(II) complexes of the antihypertensive drug nadolol

The complexation of the non-selective β-blocker nadolol, HL, 1 with copper(II) leads to formation of mono-and dinuclear complexes depending mainly on the metal-to-ligand molar ratio. The mononuclear violet complex CuL₂·2Solv, 2, was obtained in a soluble form at metal-to-ligand molar ratio Cu(II): HL ≤ 1: 10 in methanolic or slightly alkaline aqueous solutions. The dinuclear green complex Cu₂L₂Cl₂·H₂O, 3 was synthesized at Cu(II): HL ≥ 1: 2 molar ratio in methanolic solutions. The complexes were studied using spectral (UV-Vis, FT-IR, EPR), magnetochemical, thermogravimetric methods and elemental analysis. In the complexes nadolol acts as a monoanionic bidentate ligand coordinated to copper(II) through the NH-and the deprotonated OH-groups of its aminoalcohol fragment.      

铜(II)-铬(VI)复合均匀胶体粒子的制备

报导在尿素存在下通过均相沉淀法由硝酸铜和重铬酸铵制备复合均匀胶体粒子的结果．研究了一些实验参数对其组成、形态和粒子大小的影响．确定了胶体粒子的制备条件．结果观测到，由硝酸铜和重铬酸铵溶液形成了球形的多刺的粒子，它的组成为水含铅酸铜．     

Synthesis and Crystal Structures of Nickel(II) and Copper(II) Complexes of Meso-3,6,6,9-Tetramethyl-4,8-Diazaundecane-2,10-Dione Dioxime

The nickel(II) and copper(II) complexes of meso-3,6,6,9-tetramethyl-4,8-diazaundecane-2,10-dione dioxime (meso-HM-PAO) have an intramolecular hydrogen bond between cis oxime groups. [Cu(meso-HM-PAO-H)(H₂O)](NCS) crystallizes in space group P2₁/n with a = 7.692(1), b = 12.028(2), c=20.235(3) Å, β=93.03(1)°, Z = 4 and Dc=1.46 g/cm³. The final R value for this complex was 0.034 for 2223 observed reflections with I ≥ 2.5σ (I). The Cu(II) coordination is a distorted square pyramid. The Cu(II) ion is five-coorinated with the diazadioxime N atoms equatorial and water O atom axial. The Cu(II) is 0.12 Å from the equatorial plane towards the hydrate. The equatorial Cu-N distances span a narrow range, 1.953(3)-1.999(3) Å. The axial Cu-O distance is 2.314(3) Å. The thiocyanate group is almost linear. The intramolecular O ?O hydrogen bond length is 2.479(4) Å. [Ni(meso-HM-PAO-H)](ClO₄) crystallizes in space group P2₁/c with a = 14.774(3), b = 12.752(3), c = 20.035(4) Å, β = 92.94(3)°, Z = 8 and Dc = 1.51 g/cm³. The final R value for the complex was 0.053 for 4794 observed reflections with F ≥ 4σ (F). The coordination about Ni(II) is a slightly distorted square plane. The Ni(II) ion is 0.0673(7) Å from the best plane of the four donor nitrogen atoms away from the perchlorate ion. The Ni-N distances span a narrow range 1.863(4)-1.927(4) Å. There are two molecules per asymmetrical unit resulting in eight molecules being packed in an unit cell; they are bound together by van der Waals interactions. The O-H ?O bonds of these complexes give characteristic infrared absorptions as well as chemical shift of the ¹H NMR signal (Ni complex).     

Copper (II) complexes of sterically hindered o-diphenol derivatives: synthesis, characterization and microbiological studies

Cu (II) complexes with the sterically hindered diphenol derivatives 3,5-di(tert-butyl)-1,2-benzenediol (I), 4,6-di(tert-butyl)-1,2,3-benzenetriol (II) and the sulfur-containing 4,6-di(tert-butyl)-3-(2-hydroxyethylsulfanyl)-1,2-benzenediol (III) and 2-[4,6-di(tert-butyl)-2,3-dihydroxyphenylsulfanyl]acetic acid (IV) have been synthesized and characterized by elemental analysis, TG/DTA, FT-IR, ESR, XPS, XPD and conductivity measurements. Compounds I–III can coordinate in their singly deprotonated forms and act as bidentate ligands. These compounds yield Cu (II) complexes of the stoichiometry Cu(L)₂, which have square planar geometry (g_| > g_⊥ > g_e). Unlike them, compound IV behaves as a terdentate ligand, and its complex Cu(L^IV)₂ has distorted octahedral geometry. According to ESR data, only the Cu(L^II)₂ complex contains a very small amount of phenoxyl radicals. Antimicrobial activities of these ligands and their respective Cu (II) complexes have been determined with respect to Gram-positive and Gram-negative bacteria, as well as on yeasts. Their phytotoxic properties against Chlorella vulgaris 157 were also examined.     

Application of ionic liquids in palladium(II) catalyzed homogenous transfer hydrogenation

The first application of palladium(II) catalyzed homogenous transfer hydrogenations in ionic liquids is described. Cinnamic acid and its derivatives were reduced in high yields under mild conditions using ammonium formate as hydrogen donor.